BNPP - ACTIVITY 5
MICRO-SCALE CASE STUDY OF THE HYDROLOGICAL IMPACTS IN
BIODIVERSITY AND SOCIO-ECONOMIC FACTORS IN THE RIO PAZ
WATERSHED IN EL SALVADOR
(Draft)
by Ruben Guevara
ICRAF, Lima, April 2002
EXCUTIVE SUMMARY
BNPP - ACTIVITY 5: MICRO-SCALE CASE STUDY OF THE HYDROLOGICAL IMPACTS IN BIODIVERSITY AND SOCIO-ECONOMIC FACTORS IN THE RIO PAZ WATERSHED IN EL SALVADOR ENVIRONMENTAL SERVICES IN RIO PAZ, EL SALVADOR
I. BACKGROUND
In 2001, the World Bank (WB) contracted the International Centre for Research in Agroforestry (ICRAF), on behalf of the Alternatives to Slash and Burn (ASB), to carry out the project entitled “The functional value of forest-based biodiversity and its correlates: comprehensive, science-based, guidance for policy formulation”, which includes two Activities in Central America, namely: “Activity 4: Meso-scale Case Study on physical, ecological, and human geography in Central America” and “Activity 5: Micro-scale Case Study of the hydrological impacts in biodiversity and socio-economic factors in the Rio Paz watershed in El Salvador”. The project is funded by the World Bank - Netherlands Partnership Program (BNPP), and was divided in two phases.
Goals and research hypothesis for Phases I and II of the Activity 5 Case study “...will sponsor hydrological, biodiversity, and socioeconomic studies...” that seek:
· “The relation between land cover change and downstream hydrological impacts
· Trade offs and complementarities, across different land uses, among agricultural outputs, biodiversity maintenance, and hydrological functions
· Local valuation of water quality and water regulation services
· The distributional impact of hydrological externalities: who are direct agents of these externalities, who bears their burden
· Policies that promote land uses that enhance biodiversity, water quality, and markets for environmental services”
So, this Activity seeks “...to understand the trade offs and complementarities among the objectives of maintenance of hydrological processes, conservation of biodiversity, and poverty alleviation, using detailed scientific and economic data and models for a small watershed; and to assess the feasibility and desirability of instituting an environmental payment system for hydrological services.”
This report presents findings for Activity 5. The Plan of Work corresponding to Phase I have been carried out with the assistance of the Inter-American Institute for Cooperation in Agriculture in El Salvador (IICA), and the consulting firm ENDAGRO, also based in El Salvador. These two institutions have a well-established relationship with Executives in the Ministry of Environment and Natural Resources (MARN), the Ministry of Agriculture (MAG), the Foreign Ministry (MRE), and with the Vice-Presidency of El Salvador (V-P), the main counterparts that we have dealt with in the country.
Work began in September 2001, and activities in situ started in October 2001 with the involvement of ENDAGRO. Contacts were established from the onset with executives in the MANR, and the MAG, and to a lesser extent with the Office of the Vice-Presidency, so as to get them involved in all stages of the project. Presentations about the objectives of Activity 5 were made to the highest-ranking Executives of the MARN, where they are already working in the formulation of a large project on environmental services markets in El Salvador.
Less formal meetings were held with executives from MAG, MRE, and the V-P, as well as with middle managers at the MARN, and the Representative of the Organization of American States (OAS) in San Salvador.
The main liaison persons from our part in El Salvador have been Mr. Luis Silva of ENDADRO, and Dr. Gregorio Contreras from IICA.
II. GENERAL INFORMATION ON EL SALVADOR
El Salvador has a total land area of over 21,000 Km2, and a population of approximately 6 million inhabitants. In 1999, natural forests covered only 2% of the country, over 50% of its population was under 20 years of age, and close to 80% of the people is considered poor.
According to politicians, private entrepreneurs, and NGO leaders, one of the toughest challenges faced by El Salvador in the next few years is associated with water and environmental management. Executives in the MARN estimate that the present pattern of water use and management cannot continue because it is unsustainable. Some pointers follow to support this hypothesis:
· The annual average water flow in the country is estimated to be 675 m3/sec, and national demand is estimated to be 410 m3/sec. Aquifers are being drained at an annual rate of 5.2 million m3, which exceeds the estimated annual rates of infiltration or replenishment of such aquifers.
· Water is of poor quality: MARN estimates that only 2% of sewer water, and 5% of industrial effluents is treated; water in the rivers is contaminated with dozens of chemicals from industrial and agricultural activities; water contains sediments from the rampant erosion going on in all watersheds, etc..
· There are wild variations in water flow in the rivers and creeks during the year, with over abundance (including floods) in the peak of the rainy season and during tropical storms or hurricanes, which are fairly common, scarcity (including drought) in the dry season.
· Only 1 in 4 urban, and 1 in 10 rural dwellers have access to potable water, even though a majority of the population does have access to piped water.
· Over two thirds of the electricity is generated by the Rio Lempa, where its largest dam receives an estimated 15-25 million tons of sediments every year.
· Poor water quality causes a heavy toll in the economy and in people: 12,000 children die every year of diarrhea, caused by contaminated water. Additionally, water-related diseases cause a reduction in the productivity of adults, and those industries, which rely on clean water, have an extra burden in their costs of doing business.
· Demand for firewood is estimated to surpass 5.5 million m3 per year, as close to two thirds of the energy demands of the country are supplied by biomass (overwhelmingly firewood). This is maintaining a constant pressure (which is perhaps even incremental in time due to population growth) on the tree and shrub vegetation all over the country, and therefore on all the watersheds and in biodiversity, posing a bleak future for water availability in El Salvador.
A publication entitled “El desafio Salvadoreño”, and other publications dealing with water, which are in ICRAF’s possession, show more detail about these and other environmental challenges faced by El Salvador.
III. GENERAL INFORMATION ON THE RIO PAZ WATERSHED
A. INTRODUCTION
In July 1985, the Governments of El Salvador and Guatemala decided to initiate “... the integral and rational use of the Rio Paz Watershed...”, which was the stepping stone for the future collaboration of these two countries in the management and use of this bi-national watershed. Additionally, in November of 1995 during the XXV Meeting of the Central American Vice-Presidents in Costa Rica, a strategy was approved for the “Development of Common Bborders” in Central America, which included the Rio Paz Watershed as one of its priorities.
Following these mandates, Guatemala and El Salvador requested financial assistance to the OAS, through the Inter-American Council for Integral Development (CIDI), to formulate the Study for the Integrated Management Plan of the Rio Paz Watershed. The OAS approved the initial funding, and in April of 1998 the Vice Presidencies of Guatemala and El Salvador started carrying out a study leading to a general diagnosis of the Rio Paz Watershed. Within this same framework, in 1999 a group of Consultants drafted the “First Plan for the Integral Development of the Rio Paz Watershed”, requiring investments above 1/3 of a billion US dollars for the execution of activities ranging from agriculture, reforestation, and industry and including infrastructure and social services. According to a high-ranking Executive from the V-P, this Plan is the present instrument used by these two countries in negotiating bilateral and multi-lateral cooperation carrying out for development work in that watershed.
B. LAND CHARACTERIZATION
The Rio Paz Watershed has a total land area of 2,647 Km2, distributed as follows: 925 Km2 in El Salvador (34%) and 1,722 Km2 in Guatemala (66%).
As can be seen in Table 1, most of the land area is classified in as agrological classes IV, V, VI, VII and VIII (72% in El Salvador), which have high slopes and therefore a high susceptibility to erosion. The forest cover in the watershed is less than 20%, and most of the forests are already depredated due to uncontrolled firewood extraction. In the Salvadorian side, there are three small, protected areas representing 1.5% of the land area of the watershed in this country.
Total population in the watershed is 489.8 thousand inhabitants. The Salvadorian side hosts the majority of the population (66%), of which over 50% is considered extremely poor[1]. In El Salvador, 70% of the population is considered rural and the main population centers are Ahuachapan, (125,000 inhabitants), Chalchuapa (60,000 inhabitants), Atiquizaya (45,000 inhabitants).
The main commercial activities include: production of coffee, staple foods, fruits (bananas, oranges, coconuts), and rice), trans-border trade, and petty commerce in the main population centers. There are three important border points along the Rio Paz River, between Guatemala and El Salvador, which serve as catalyzers to a dynamic commercial activity between the peoples of the two countries.
Population density is much higher in El Salvador, as is the percentage of the population engaged in economic activities (PEA). Reported birth rates seem relatively very low on both sides (less than 2.5%), but it is probably because these are actually net birth rates.
The main biophysical and social characteristics of the watershed, in Guatemala and El Salvador, are also shown in Table 1.
C. HYDROLOGICAL INFORMATION
The watershed has 56 sub-watersheds, out of which 21 are located in El Salvador, where the Rio Pampe is the most important effluent from the standpoint of water volume. This river originates at elevations above 2000 masl in the volcanic Cordillera Occidental mountain range. Other important effluents in the watershed are Trapichito, Chingo o Jerez, Magdalena, Calera de San Marcos, El Silencio, Chiquito and San Nicolas rivers.
Figure XXX shows a map depicting the sub-watersheds.
TABLE 1. Biophysical and social characteristics of the Rio Paz watershed
Characteristics / Guatemala / El Salvador / WatershedLand area (km²) / 1722 / 925 / 2,647
Sub-watersheds / 35 / 21 / 56
Land use capacity (agrological classes) / II-III (28%), IV-V (18%), VI-VII-VIII (44%) / II-III (38%), IV-V (18),
VI-VII-VIII (54%) / II-III (32%), IV-V (18%), VI-VII-VIII (48%)
Life zones / 3 (?) / 6 / ??
Forest cover (%) / 29 / 15(*) / 24
Main crops / Ssugarcane, mangos, prunes, oranges, coconuts, staple food (corn, beans, sorghum) / Ccoffee, bananas, oranges, coconuts, staple food (corn, beans, sorghum, rice) / Sugar cane, coffee, staple food, mangos, oranges
Protected areas / 1 / 3 / 4
Total Population (000) / 168.9 / 320.9 / 489.8
Rural population (000) / 135 / 221 / 356
Population density ppkm2 (**) / 98 / 299 / 185
Birth rate (%) / 1.54 / 2.01 / 1.85
PEA (%) / 25 / 43 / 37
Rain waterfall (mm) / 1500 / 1700 / ----
* Excludes coffee plantations, which are usually associated with tree crops.
** People per square kilometer
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The watershed has three water flow measurement stations: San Lorenzo in Rio Pampe, La Hachadura and El Jobo in Rio Paz, which have had major gaps in recording flow data. Measurements in the three water flow measuring stations started: a) San Lorenzo Lorenzo: 1961, b) La Hachadura: 1962, c) El Jobo: 1966. There are also 10 pluviometric (rainfall measurement) stations in El Salvador, and 24 in Guatemala.
The annual average annual precipitation in Guatemala is 1,500 mm and in El Salvador is 1,700mm. Rainfall distribution in the watershed varies from south to north, with the highest rainfall in the highlands in El Salvador side, with up to 2,000 mm of rainfall per year, and the lowest rainfall - with an average of 1,1000 mm - in the northernmost section of the Guatemalan side.
An Isoyetes map (lines depicting similar rainfall) is shown in Figure 1, providing the historical detail of these rainfall patterns within the watershed.
Rainfall distribution throughout the year is shown in Table 2, for El Salvador, where the average rainfall in three representative measuring stations can be seen.
TABLE 2. Average rainfall in selected pluviometric stations in El Salvador
Pluviometric station / J / F / M / A / M / J / J / A / S / O / N / D / Annual Average (mm)Apaneca, Santa. Leticia / 8 / 0 / 14 / 32 / 220 / 427 / 326 / 381 / 452 / 238 / 55 / 14 / 2,167
Atiquizaya / 3 / 3 / 5 / 50 / 166 / 303 / 306 / 303 / 311 / 181 / 24 / 3 / 1,669
La Hachadura / 4 / 2 / 2 / 51 / 147 / 310 / 227 / 284 / 347 / 187 / 33 / 5 / 1,599
Mean water flow in La Hachadura Station is 28.1 m3/second (the estimated volume from the Guatemalan side is equivalent to 17.2 m3/second and in El Salvador side it is 10.9 m3/second). In the summer the mean water flow is 10.5 m3/second and in the rainy season 45.7 m3/second .second. Historical data shows a tremendous variability in water flow from time to time, depending in some cases on natural phenomena, such as tropical storms, hurricanes, and the like, with recorded very high picks in certain years (Table 3 and Figure 2). In the driest month water flows get to be as low as less than 2 m3/second.